/*
 * Copyright (C) 1997-2001 Id Software, Inc.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or (at
 * your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 *
 * See the GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
 * 02111-1307, USA.
 *
 * =======================================================================
 *
 * This file implements interpolation between two frames. This is used
 * to smooth down network play
 *
 * =======================================================================
 */

#include "header/client.h"

void CL_CheckPredictionError (void) {
	int		frame;
	int		delta[3];
	int		i;
	int		len;

	if (!cl_predict->value || (cl.frame.playerstate.pmove.pm_flags & PMF_NO_PREDICTION))
		return;

	/* calculate the last usercmd_t we sent that the server has processed */
	frame = cls.netchan.incoming_acknowledged;
	frame &= (CMD_BACKUP-1);

	/* compare what the server returned with what we had predicted it to be */
	VectorSubtract (cl.frame.playerstate.pmove.origin, cl.predicted_origins[frame], delta);

	/* save the prediction error for interpolation */
	len = abs(delta[0]) + abs(delta[1]) + abs(delta[2]);

    /* 80 world units */
	if (len > 640) {
		/* a teleport or something */
		VectorClear (cl.prediction_error);

	} else {
		if (cl_showmiss->value && (delta[0] || delta[1] || delta[2]) )
			Com_Printf ("prediction miss on %i: %i\n", cl.frame.serverframe,
			            delta[0] + delta[1] + delta[2]);

		VectorCopy (cl.frame.playerstate.pmove.origin, cl.predicted_origins[frame]);

		/* save for error itnerpolation */
		for (i=0 ; i<3 ; i++)
			cl.prediction_error[i] = delta[i]*0.125f;
	}
}

void CL_ClipMoveToEntities ( vec3_t start, vec3_t mins, vec3_t maxs, vec3_t end, trace_t *tr ) {
	int			i, x, zd, zu;
	trace_t		trace;
	int			headnode;
	float		*angles;
	entity_state_t	*ent;
	int			num;
	cmodel_t	*cmodel;
	vec3_t		bmins, bmaxs;

	for (i=0 ; i<cl.frame.num_entities ; i++) {
		num = (cl.frame.parse_entities + i)&(MAX_PARSE_ENTITIES-1);
		ent = &cl_parse_entities[num];

		if (!ent->solid)
			continue;

		if (ent->number == cl.playernum+1)
			continue;

		if (ent->solid == 31) {
			/* special value for bmodel */
			cmodel = cl.model_clip[ent->modelindex];

			if (!cmodel)
				continue;

			headnode = cmodel->headnode;
			angles = ent->angles;

		} else {
			/* encoded bbox */
			x = 8*(ent->solid & 31);
			zd = 8*((ent->solid>>5) & 31);
			zu = 8*((ent->solid>>10) & 63) - 32;

			bmins[0] = bmins[1] = -(float)x;
			bmaxs[0] = bmaxs[1] = (float)x;
			bmins[2] = -(float)zd;
			bmaxs[2] = (float)zu;

			headnode = CM_HeadnodeForBox (bmins, bmaxs);
			angles = vec3_origin; /* boxes don't rotate */
		}

		if (tr->allsolid)
			return;

		trace = CM_TransformedBoxTrace (start, end,
		                                mins, maxs, headnode,  MASK_PLAYERSOLID,
		                                ent->origin, angles);

		if (trace.allsolid || trace.startsolid ||
		        trace.fraction < tr->fraction) {
			trace.ent = (struct edict_s *)ent;

			if (tr->startsolid) {
				*tr = trace;
				tr->startsolid = true;

			} else
				*tr = trace;

		} else if (trace.startsolid)
			tr->startsolid = true;
	}
}

trace_t		CL_PMTrace (vec3_t start, vec3_t mins, vec3_t maxs, vec3_t end) {
	trace_t	t;

	/* check against world */
	t = CM_BoxTrace (start, end, mins, maxs, 0, MASK_PLAYERSOLID);

	if (t.fraction < 1.0)
		t.ent = (struct edict_s *)1;

	/* check all other solid models */
	CL_ClipMoveToEntities (start, mins, maxs, end, &t);

	return t;
}

int		CL_PMpointcontents (vec3_t point) {
	int			i;
	entity_state_t	*ent;
	int			num;
	cmodel_t		*cmodel;
	int			contents;

	contents = CM_PointContents (point, 0);

	for (i=0 ; i<cl.frame.num_entities ; i++) {
		num = (cl.frame.parse_entities + i)&(MAX_PARSE_ENTITIES-1);
		ent = &cl_parse_entities[num];

		if (ent->solid != 31) /* special value for bmodel */
			continue;

		cmodel = cl.model_clip[ent->modelindex];

		if (!cmodel)
			continue;

		contents |= CM_TransformedPointContents (point, cmodel->headnode, ent->origin, ent->angles);
	}

	return contents;
}

/*
 * Sets cl.predicted_origin and cl.predicted_angles
 */
void CL_PredictMovement (void) {
	int			ack, current;
	int			frame;
	int			oldframe;
	usercmd_t	*cmd;
	pmove_t		pm;
	int			i;
	int			step;
	int			oldz;

	if (cls.state != ca_active)
		return;

	if (cl_paused->value)
		return;

	if (!cl_predict->value || (cl.frame.playerstate.pmove.pm_flags & PMF_NO_PREDICTION)) {
		/* just set angles */
		for (i=0 ; i<3 ; i++) {
			cl.predicted_angles[i] = cl.viewangles[i] + SHORT2ANGLE(cl.frame.playerstate.pmove.delta_angles[i]);
		}

		return;
	}

	ack = cls.netchan.incoming_acknowledged;
	current = cls.netchan.outgoing_sequence;

	/* if we are too far out of date, just freeze */
	if (current - ack >= CMD_BACKUP) {
		if (cl_showmiss->value)
			Com_Printf ("exceeded CMD_BACKUP\n");

		return;
	}

	/* copy current state to pmove */
	pm.trace = CL_PMTrace;
	pm.pointcontents = CL_PMpointcontents;

	pm_airaccelerate = atof(cl.configstrings[CS_AIRACCEL]);

	pm.s = cl.frame.playerstate.pmove;

	frame = 0;

	VectorSet (pm.mins, -16, -16, -24);
	VectorSet (pm.maxs,  16,  16, 32);

	/* run frames */
	while (++ack < current) {
		frame = ack & (CMD_BACKUP-1);
		cmd = &cl.cmds[frame];

		pm.cmd = *cmd;
		Pmove (&pm);

		/* save for debug checking */
		VectorCopy (pm.s.origin, cl.predicted_origins[frame]);
	}

	oldframe = (ack-2) & (CMD_BACKUP-1);
	oldz = cl.predicted_origins[oldframe][2];
	step = pm.s.origin[2] - oldz;

	if (step > 63 && step < 160 && (pm.s.pm_flags & PMF_ON_GROUND) ) {
		cl.predicted_step = step * 0.125f;
		cl.predicted_step_time = cls.realtime - cls.frametime * 500;
	}

	/* copy results out for rendering */
	cl.predicted_origin[0] = pm.s.origin[0]*0.125f;
	cl.predicted_origin[1] = pm.s.origin[1]*0.125f;
	cl.predicted_origin[2] = pm.s.origin[2]*0.125f;

	VectorCopy (pm.viewangles, cl.predicted_angles);
}

